Blazor redirect on policy failed

Question

I need to react differently based on which authorization policy failed. So, if PolicyA failed when user tried to navigate to pageA (which requires PolicyA), I would like to redirect to pageB.

Is this possible in Blazor WASM?

Answer 1

One option is to use IAuthorizationService and the cascaded parameter of type Task<AuthenticationState> like this:

@using Microsoft.AspNetCore.Authorization
@inject IAuthorizationService AuthorizationService
@inject NavigationManager NavigationManager

...

@code {
    [CascadingParameter]
    private Task<AuthenticationState> authenticationStateTask { get; set; }

    protected async override Task OnInitializedAsync()
    {
        var user = (await authenticationStateTask).User;

        if ((await AuthorizationService.AuthorizeAsync(user, "PolicyA"))
            .Succeeded)
        {
            NavigationManager.NavigateTo("pageB");
        }

        // rest of the code
    }
}

Another option is to use AuthorizeView component like this:

@inject NavigationManager NavigationManager

<AuthorizeView Policy="PolicyA">
    <Authorized>
        @* Page content *@
    </Authorized>
    <NotAuthorized>
        @{ Navigation.NavigateTo("pageB"); }
    </NotAuthorized>
</AuthorizeView>

@code {

}